• Transactions of the Korean Society of Automotive Engineers
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• v.9 no.5
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• pp.195-205
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• 2001

The mechanical properties of aluminum honeycomb on the direction of axial crushing under quasistatic loading test was investigated. The crushing process was simulated numerically by full-scale finite element models. Simulations reproduce the experimental results both qualitatively as well as quantitatively. From the investigation, we suggested the constitutive model of energy absorbing honeycomb structure for large scale impact analysis. Real impact test of the WB(Moving Deformable Barrier) was carried and compared with finite element simulation. Constitutive model used in the numerical simulation had a good correlation with experiment. By suggesting the optimizing method fur honeycomb cell configuration design, relationship between cell configuration and crush strength is studied.

• Advances in nano research
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• v.15 no.2
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• pp.141-153
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• 2023

The main objective of this paper is to develop the finite element study on the nonlinear free vibration of functionally graded nanocomposite spherical shells reinforced with graphene platelets under the first-order shear deformation shell theory and von Kármán nonlinear kinematic relations. The governing equations are presented by introducing the full asymmetric nonlinear strain-displacement relations followed by the constitutive relations and energy functional. The extended Halpin-Tsai model is utilized to specify the overall Young's modulus of the nanocomposite. Then, the finite element formulation is derived and the quadrilateral 8-node shell element is implemented for finite element discretization. The nonlinear sets of dynamic equations are solved by the use of the harmonic balance technique and iterative method to find the nonlinear frequency response. Several numerical examples are represented to highlight the impact of involved factors on the large-amplitude vibration responses of nanocomposite spherical shells. One of the main findings is that for some geometrical and material parameters, the fundamental vibrational mode shape is asymmetric and the axisymmetric formulation cannot be appropriately employed to model the nonlinear dynamic behavior of nanocomposite spherical shells.

• Structural Engineering and Mechanics
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• v.60 no.5
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• pp.829-849
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• 2016

In this paper, experimental as well as numerical analysis of Glass Fiber Reinforced Polymer (GFRP) laminated composite has been presented under ballistic impact with varying projectile nose shapes (conical, ogival and spherical) and incidence velocities. The experimental impact tests on GFRP composite plate reinforced with woven glass fiber ($0^{\circ}/90^{\circ}$)s are performed by using pneumatic gun. A three dimensional finite element model is developed in AUTODYN hydro code to validate the experimental results and to study the ballistic perforation characteristic of the target with different parametric variations. The influence of projectile nose shapes, plate thickness and incidence velocity on the variation of residual velocity, ballistic limit, contact force-time histories, energy absorption, damage pattern and damage area in the composite target have been studied. The material characterization of GFRP composite is carried out as required for the progressive damage analysis of composite. The numerical results from the present FE model in terms of residual velocity, absorbed energy, damage pattern and damage area are having close agreement with the results from the experimental impact tests.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.226-231
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• 2007

This paper studied on the impact fracture modeling techniques of spherical dome with MACOR glass-ceramic. The glass ceramic material has bigger compressive strength than the tensile strength and endure well at high temperature. The fracture simulation under shock perssure was performed by the finite element method with nonlinear code LS-Dyna. The simulation was carried out by 3 type dome models under step impact pulse shape. 4-node shell element and 8-node solid element were used for analysis.

• Journal of the Korean Society of Safety
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• v.12 no.4
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• pp.169-179
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• 1997

The dynamic response of the human brain to direct impact was studied by three-dimensional finite element modeling. The model includes a layered shell closely representing the cranial bones with the interior contents occupied by an incompressible continuum to simulate the brain. Falx and tentorium modeled with 4 node membrane element were also incorporated. The computed pressure-time histories at 4 locations within the brain element compared quite favorably with previously published experimental data from cadaver experiments. Therefore, the purpose of this study was to determine the effects of the impact direction on the dynamic response of the brain in children. A parametric study was subsequently conducted to identify the model response when the age and impact site were varied.

• Structural Engineering and Mechanics
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• v.19 no.3
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• pp.281-295
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• 2005

An analytical method is presented to solve the elastodynamic problem of finitely long hollow cylinder subjected to torsional impact often occurs in engineering mechanics. The analytical solution is composed of a solution of quasi-static equation satisfied with the non-homogeneous boundary condition and a solution of dynamic equation satisfied with homogeneous boundary condition. The quasi-static solution is obtained directly by solving the quasi-static equation satisfied with the non-homogeneous boundary condition. The solution of the non-homogeneous dynamic equation is obtained by means of finite Hankel transform on the radial variable, r, Laplace transform on time variable, t, and finite Fourier transform on axial variable, z. Thus, the solution for finitely long, hollow cylinder subjected to torsion impact is obtained. In the calculating examples, the response histories and distributions of shear stress in the finitely long hollow cylinder subjected to an exponential decay torsion load are obtained, and the results have been analyzed and discussed. Finally, a dynamic finite element for the same problem is carried out by using ABAQUS finite element analysis. Comparing the analytical solution with the finite element solution, it can be found that two kinds of results obtained by means of two different methods agree well. Therefore, it is further concluded that the analytical method and computing process presented in the paper are effective and accurate.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.12
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• pp.2656-2661
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• 2002

Multiple impact models to examine the effect of stress interference are proposed and investigated. The single shot model analysis, which used various shot ball conditions, was carried out to compare with multiple impacts analysis. Then the multiple impact analysis were performed to predict the effect of the shot ball distances. The results showed that the stress interference in the multiple impact model significantly reduced the maximum value of the compressive residual stresses. The residual stress profiles were strongly effected by the shot ball distances. The multiple impact model can simulate a realistic shot peening process rather than a single shot model does. It is concluded that the proposed model predicts the real process more accurately.

• Structural Engineering and Mechanics
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• v.55 no.2
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• pp.263-280
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• 2015

This paper describes a study of the collision of hard steel spheres against aluminium thin circular plates at speeds up to 140 m/s. The tests were monitored by a high speed camera and a chronoscope, which allowed the determination of the ballistic limit and the plate deformation pattern. Quasi-static material parameters were obtained from tests on a universal testing machine and dynamic mechanical characterization of two aluminium alloys were conducted in a split Hopkinson pressure bar. Using a damage model, the perforation of the plates was simulated by finite element analysis. Axisymmetric, shell and solid elements were employed with various parameters of the numerical analysis being thoroughly discussed, in special, the dynamic model parameters. A good agreement between experiments and the numerical analysis was obtained.

• Tribology and Lubricants
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• v.27 no.1
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• pp.34-39
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• 2011

In this study, finite element analysis of particle-surface collision using 2-dimensional elements was performed to observe the effects of abrasive size and impact angle. The result of the simulation on the change in abrasive size revealed that larger abrasive particle induced larger contact stress due to force transfer through slurry fluid as the particle moved and pushed the fluid. This observation brought an important finding that the slurry fluid could make the workpiece surface soften and then change the mechanical properties of the surface layer such as elastic modulus and yield strength. As for the impact angle, it was found that the contact stress increased with the angle of impact and jumped up at a specific angle. Such result would be attributed to the complex effects of the impact velocity and angle.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.11
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• pp.2805-2816
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• 1994

This paper describes dynamic finite element analyses performed to study the dynamic behaviors of a shipping container under the impact onto rigid target due to the accidental fall from the hight of 9 m. Using two and three dimensional techniques, the shipping container which gave the maximum damage, ten different drop orientations are considered ; at intervals of $5^{\circ}$ from $45^{\circ}$ to $90^{\circ}$ According to the present results, the orientation of the shipping container which gave the maximum damage is $85^{\circ}$ from horizontal for oblique drop in the primary impact. In the optimal design of the shipping container, the impact limiter material must be considered importantly because it's proper selection affects the weight and the manufacturing cost of the shipping container. The analysis of the shipping container in this paper demonstrated that the shipping container is structurally sound relative to the regulatory drop test requirements.